268 



OSTEOLOGY OF TUBINARES AND STEGANOrODES. 



Just the faintest trace of a propubis is seen in the pelvis of this Ful- 

 mar, while the post-pubis is narrow, nearly straight, slightly expanded 

 behind where its upper edge meets the aforesaid process of the ischium, 



beyond which it soon terminates in a square- 

 cut end that in life is produced in a cartilage 

 of an equal width for a short distance farther. 

 The caudal vertebrae axe all supplied with 

 chevron bones, except the first two or three 

 anterior ones. They become progr essively 

 larger from before backward, and are all 

 bifid, being profoundly cleft in an antero- 

 posterior direction. This is continued to the 

 lower angle of the pygostyle, where it is rep- 

 resented in most specimens by a notch. 



These chevron bones are anchylosed to the 

 vertebra? over which they stand, and their 

 bases are produced in front so as to encroach 

 slightly upon the segment next in front of 

 them, when the series is articulated in situ. 

 The pygostyle is a large quadrate bone, 

 with sharpened anterior border, but thick- 

 ened behind. A clean, circular foramen is 

 generally to be found at its infero-posterior 

 angle, indicating the point of union of the 

 two anterior vertebrae that compose this com- 

 pound bone, it being a vacuity between their 

 chevron bones. 



Of the appendicular .skeleton. — We find that 

 both the pectoral and pelvic limbs in the 

 Fulmars are non-pneumatic, and much ani- 

 mal matter is contained in the large cavities 

 of the long bones composing them. 



When the skeleton of the pectoral limb is closed alongside the body 

 in situ the bones of the antibrachium are but very slightly in advance 

 of the humerus, the ulna being nearly of a length with that bone and the 

 radius slightly longer. 



The shafts of these long bones are all notably straight, that of the 

 humerus being subcylindrical on section and showing scarcely any cur- 

 vature viewed from either aspect. 



'flic head of the humerus is fashioned as we found it in the Petrels, 

 but tlic radial crest is more prominent and of a triangular form. Its 

 distal extremity supports a large ectocondyloid process, between which 

 and the opposite border, on the palmar aspect, a conspicuous concavity 

 exists, as deseribed for Oceanodroma. 



Eodgers' Fulmar, as far as I can learn from the excellent material 

 before me, is devoid of any such thing as sesamoids about the elbow- 



Fir.. 11. The pelvis of Fulmans 

 glacialis rodgi rsii, seen from above. 

 Same specimen as .shown in Fig. 10. 

 Life size. By the author. 



